Tangkoko, Sulawesi. They were all hiding in a hollow tree because of the strong heat in the early afternoon so we were lucky that one of them peered out!

Quoting from this reference:
http://guideplanet.com/introducing-the-smallest-primate-in-the-world-on-tangkoko-national-park/

<<Tarsius has O blood type, similar to humans. Its head can rotate up to 180 degrees. Although it has a tiny body, Tarsius is able to jump from one tree to another up to 3 meters of distance. The unique thing is that Tarsius cannot walk on the ground. If it falls from a tree, it will immediately jump to it and climb it back up.

Tarsius is a nocturnal animal. It spends most of its day sleeping and hanging on a tree branch, and then it goes hunting for food at night. It has huge eyes, probably even bigger than its brain, for a better night vision.

Even if Tarsius is considered as a rare species, it is very difficult to conserve them. They are very shy and they tend to run away when they encounter humans--who can blame them!--

It is also impossible to breed them on a conservation area, outside their natural habitat because they will get stressed out. If a Tarsius gets stressed out, he will hurt himself and commit suicide.>>

I am not 100% sure have the species correct. I saw this little guy in Tangkoko Reserve, North Sulawesi. Quite amazing creatures with their enormous eyes which gives the 360 degree vision. In fact their eye sockets are larger than their brain cavities!
These are also the only completely carnivorous primate.